The present invention relates to a mounting arrangement for supporting a substrate having an optical pattern formed one surface, onto a mount plate that is connected to an instrument of a bench. The optical pattern can be a computer generated hologram (CGH) that is to be used in testing of aspheric optical components.
U.S. Pat. No. 5,530,547 describes a system for aligning optical elements for testing aspheric optical components. In the '547 patent, a frame is provided with spherical (ball shaped) mounts that are supported in turn on positioning pins carried on a mount plate. The mount plate is supported on a base, which in turn is capable of being attached to an optical table, rail, bench or the like. The mount plate illustrated in the '547 patent works well with smaller optical elements, but when larger CGH patterns are to be checked, a peripheral frame becomes large and difficult to keep stress free. The frame should be made of a material that has near zero thermal expansion coefficient, such as Invar, to insure accuracy. Frames for larger substrates carrying optical patterns cannot readily be made of Invar or similar materials because of the high material weight and the high cost. Using aluminum frames for the larger optical patterns has disadvantages, particularly in relation to likely movement of elastomers used for supporting for the optical element and the possible distortion of the glass supporting the optical element.